A compactly tufted annual, 1 1/2–8 in. high, very similar to S. barbatus. Culms prostrate, geniculately ascending or suberect, numerous, very slender or filiform, simple or branched at the base, 2–3-noded, glabrous, smooth; upper internodes finally exserted. Leaf-sheaths bearded at the mouth with fine spreading hairs, otherwise glabrous, smooth; ligule a ciliate rim; blade very narrowly linear, acute, 1/2–6 in. long, 1/4–1 lin. wide, flat, or setaceously convolute, sparingly hairy or glabrous, smooth. Panicle contracted, usually very dense, lanceolate to oblong or elliptic, 1/2–2 in. long, 1/8– 3/4 in. wide; branches very slender; pedicels finally disarticulating from the branches, much shorter than the spikelets, minutely hispidulous. Spikelets narrow, at length gaping, 2 1/2–3 1/2 lin. long, greenish. Glumes acute, 2 1/2–3 1/2 lin. long, green on the prominently nerved back, with rather broad white margins, glabrous, smooth or minutely scaberulous on the nerves; lower lanceolate to oblong-lanceolate, 5–7-nerved; upper lanceolate, 3–5-nerved. Florets 5–8. Valves elliptic-oblong or oblong when flattened, 1 1/4–1 2/3 lin. long, 2-lobed, with the acutely acuminate lobes one-third to half the length of the valve, mucronate in the sinus, hairy below the middle with fine acute hairs. Valvules about three-fourths the length of the valves. Anthers 1/6 lin. long. Grain obovate-oblong, 1/2 lin. long.
